1. Field of the Invention
The present invention relates to an inkjet printer, and more particularly to a method and a device for sensing the quantity of remaining ink by scanning and comparing print letters through a wider scanner width than a print width of an inkjet print head.
2. Description of the Related Art
A cartridge of an inkjet printer exemplary of contemporary practice in the art stores a certain quantity of ink, and forms print letters by jetting stored ink on the paper through the jetting device. After a certain period of time, the ink stored in the cartridge is consumed and is replaced and again used after being refilled. Accordingly, a manufacturer of an inkjet printer informs a user of the quantity of remaining ink and lets the user know the time for the replacement of a cartridge.
A central processing unit (CPU) inside of a printer, in order to determine the quantity of remaining ink, calculates the jetted quantity of ink by counting the number of inkdrops jetted through the head, when printing begins. After determining the value, knowing the quantity of ink stored in a cartridge as a number of drops stored in advance, and after the number of jetted inkdrops is determined through use of a counter, the two values are compared. Based on the total drop number of the quantity of ink stored in advance, the CPU judges whether the value of drops jetted through a head reaches a certain value, and if the value reaches the certain value, the CPU stops the printing motion and indicates that the ink has been totally consumed through an indicator.
Also, exemplary of contemporary practice in the art for determining the quantity of remaining ink is to check out the quantity of remaining ink by knowing the quantity of ink initially inside of an inkjet print head, then adding up the number of dots jetted through a nozzle at each time of printing, and analogizing the remaining ink based upon the initial quantity of ink and the number of dots jetted through the nozzle. Accordingly, it frequently occurs that the printer will continue to print even though a sufficient quantity of ink does not remain, because an accurate quantity of consumed ink cannot be counted. Also, on the contrary, printing stops after indicating a message for replacing a cartridge, even though ink remains. As a result, waste of paper can occur, as well as problems of inconvenience, when a printer is used.
U.S. Pat. No. 4,935,751 to Hamlin entitled Level Sensor For Ink Bag, discloses an ink device having means for determining the amount of ink remaining in an ink bag including a rigid, rectangular box which has a window in the top, a collapsible ink bag in the container, one side of the ink bag being secured to the corresponding side of the container and the opposite side of the ink bag having a rigid plate or strip secured to its lower head so that the top edge of the plate is visible through the window.
U.S. Pat. No. 4,940,997 entitled Out-Of-Ink Sensing Method, to Hamlin, et al. disclose an ink-jet printer, wherein a ball check-valve is used over the ink outlet of an ink bag to interrupt the flow of ink and/or air to the ink bladder when the ink supply in the bag falls below a predetermined level.
U.S. Pat. No. 4,973,993 entitled Ink-Quantity And Low Ink Sensing For Ink-jet Printers, to Allen, discloses means for computing remaining ink and for sensing a true low-ink and out-of-ink condition. It is disclosed ink is supplied to a printhead by an elastic bladder which is periodically refilled from an ink bag, with the bladder being designed to collapse in a repeatable manner as ink is consumed. A sensor probe is disclosed which moves along the bladder's collapse axis, dimples the bladder prior to printing to initialize the collapse mode, with the probe position along the axis being measured when its sensitive tip touches the bladder. It is disclosed the difference between the bladder positions before and after refill is used in an algorithm to compute the bladder's volumetric change to indicate the ink consumed on each print cycle, and gives the quantity of ink remaining when subtracted from an initial value.
U.S. Pat. No. 5,079,570 entitled Capillary Reservoir Binary Ink Level Sensor to Mohr, et al., disclose an ink level sensor provided for detecting a level of ink in an ink cartridge containing a capillary reservoir, such as foam, therein. It is disclosed that the ink level sensor is a binary fluidic indicator, which provides both a human and machine readable indication of the level of the ink. Various embodiments are disclosed of the ink level sensor including a two-port sensor, a one-port sensor and a pair of fluidically -connected needles of different length.
U.S. Pat. No. 5,329,373 entitled Facsimile Apparatus Having Original Document And Recording Medium Conveying Systems to Hayashi, et al., disclose a facsimile apparatus which includes a recording unit including a serial ink-jet recording head and a replaceable ink cartridge. It is disclosed the apparatus includes an upper surface lid, which is openably provided on the upper surface of the main body and allows replacement of the ink cartridge.
U.S. Pat. No. 5,359,353 entitled Spring-Bag Printer Ink Cartridge With Volume Indicator to Hunt, et al., disclose and inkjet pen supply cartridge having a spring biased ink bag with a visual indication of remaining ink quantity. It is disclosed that the spring-bag is contained in a rigid cartridge and a pair of flexible tape members are cemented or welded, one to each side of the spring-bag, and extend generally parallel toward a narrow end surface of the cartridge at which they overlap and can be viewed through a window.